In recent years cellular telephones have become increasingly popular. A cellular telephone is just one example of what is referred to in telephone parlance as a “mobile station” (MS) or “mobile terminal”. A mobile station can take on various forms other than a cellular telephone, including a computer (e.g. a laptop computer) with mobile termination capabilities. A mobile station comprises of a so-called mobile equipment (ME) and a subscriber identification module (SIM).
Telecommunication services are provided between a cellular telecommunications network and a mobile station over an air interface, e.g. over radio frequencies. At any moment, an active mobile station is in communication over the air interface with one or more units of the communications network such as base transceiver stations (BTSs). Base transceiver stations (BTS) in turn are managed by other units of the network such base stations controllers (BSCs), also known as radio network controllers (RNCs). A base station controller (BSC) together with its base transceiver stations forms a base station subsystem (BSS). The base station controllers of a base station subsystem are connected via further units of the network, e.g. control nodes, to a core telecommunications network. Control nodes can take on various forms, depending on the types of services of networks to which the control nodes are connected. A well known embodiment of a control node is a mobile switching center (MSC), which is often associated with a visiting location register (VLR).
The network is described using GSM-type terminology. However, as is apparent to any person skilled in the art, the present invention may be employed in other radio communication networks, e.g. UMTS (Universal Mobile Telecommunications System), etc., as well. Therefore, the use of GSM-type terminology shall not be construed as limiting the scope of the invention. The mobile switching center in UMTS-type telecommunications networks is still denoted as mobile switching center (MSC). The equivalents of the base stations controller and the base transceiver station of GSM-type telecommunications networks however are denoted as radio network controller (RNC) and Node-B respectively in UMTS-type telecommunications networks.
An owner of a mobile station typically enters into a contract or subscription agreement with a service provider (e.g., a company which operates the telecommunications network through which the mobile station engages in telecommunications connections). As part of the subscription agreement, the mobile station is categorized as belonging to one of several access classes available on the network. Subscription data from the subscription agreement is stored in a record maintained e.g. in a home location register (HLR) for the mobile station. Each subscriber having a mobile station is assigned a unique International Mobile Subscriber Identity (IMSI). The international mobile subscriber identity is stored in the subscriber identification module.
A mobile subscriber, that is to say the user of the mobile station, who roams freely within the network, is able to do so because the network stores information about a location of the mobile station. This makes it possible for the mobile subscriber to receive a call regardless of location. To keep the network up to date with the subscriber's location, the mobile station informs the network whenever it changes a location area (LA). This is called location updating. Location areas (LAs) are defined by location area identities (LAI), comprising a mobile country code (MCC), a mobile network code (MNC) and a local area code (LAC).
A base transceiver station broadcasts a location area information to a mobile station. A base station controller/radio network controller broadcasts a routing area (RA) and the location area (LA) to the mobile station. The mobile station uses the received mobile network code (MNC) and compares the value with a mapping table, which is stored either in the mobile equipment (ME) or in the subscriber identification module (SIM). The mapping table translates the mobile network code (MNC) into a text string, which can be displayed on the display of the mobile equipment (ME). The text string comprises an alphanumeric representation of the network identity (NI), e.g. “T-D1”, “O2”, etc.
The problem with this handling is that it is too static. Therefore there is no provision to account for changing names of the service providers or the actual branding for mobile stations (MS) on the market. Furthermore with communication networks jointly used by at least two service providers, the subscriber is likely to be displayed with a wrong network identity (NI), e.g. “D1” instead of “O2” or vice-versa.
The 3GPP (3rd generation partnership project) specification TS 22.042—Network Identity and Time Zone (NITZ), Version 5.1.0 published Jun. 18, 2003, describes a mechanism to transfer a network identity (NI) within a mobility management (MM) message towards the mobile station (MS). However, even with NITZ it is not possible to send different network identities to subscribers of different service providers.